| 摘要 |
PURPOSE:To obtain a fine-grain goethite having uniform grain size, in which dendritic grains are not included and with the axial ratio increased by adding an aq. soln. of alkali carbonate to a mixture of green rust with a goethite nucleus grain and introducing an oxygen-contg. gas into the soln. CONSTITUTION:An aq. ferrous salt soln. is allowed to react with the aq. solns. of alkali hydroxide and alkali carbonate or the mixed aq. soln. of alkali hydroxide and alkali carbonate in the amt. (0.15-0.85 equivalent) less than the equivalent to the Fe<2+> in the soln. to obtain a ferrous salt reaction soln. contg. a ferrous hydroxide colloid or iron-contg. precipitate. An oxygen-contg. gas is introduced into the reaction soln. to oxidize the colloid to obtain a ferrous salt reaction soln. contg. green rust and a goethite nucleus grain generated via the green rust. An aq. alkali carbonate soln. in the amt. more than the equivalent to the Fe<2+> in the soln. is added to the reaction soln. contg. 10-30% Fe<2+>, and an oxygen-contg. gas is introduced to grow the goethite nucleus grain. |
